1. Field of the Invention
The invention relates to the clamping or locking of a part in a given position in which it is to undergo one or more operations, such as machining and in particular machining or milling by electrochemistry. The clamping system according to the invention more particularly relates to the holding of fragile or very thin portions of the part to be worked and which are liable to move or vibrate during machining.
2. Description of the Prior Art
Reference is firstly made to FIG. 1. In connection with the manufacture of the blades of compressors of turbine engines, such as turbo-jets, there is a need to finish the shaping of the two functional surfaces of the blades by electrochemical machining. It is pointed out that the blade is firstly shaped by forging so as to provide a blank.
FIG. 1, which shows this electrochemical finishing phase, reveals all the essential elements for this operation, even for the prior art. Thus, it is possible to see the part 1 fixed by its foot or root 1A in a fixing block 5, the entity being placed within a machining cage 3. The upper portion has one or more electrochemical liquid intakes 4 and the lower portion has an outlet 7 for said same electrochemical liquid. Thus, there is a circulation of said electrochemical liquid around the blade 1 to be shaped.
This shaping is obtained by means of two electrodes 2, the shape of the ends of which is complimentary to that of the lateral faces of the blade 1. The blank of the blade 1 is fixed by its root 1A in the fixing block 5, the electrodes 2 being approached by said two lateral surfaces of the blade 1. The blade is connected to the positive terminal of the system, while the electrodes 2 are connected to the negative terminal. Thus, ions are torn away from the two lateral surfaces of the blade 1. Thus, within a few minutes, advancing the electrodes makes it possible to reduce the blade blank thickness from 5 to approximately 1 mm or less.
As from such reduced thicknesses vibration phenomena occur, particularly if the blade is longer than a few centimeters. Obviously the vibration phenomenon is prejudicial to the quality of the finish of the two faces of the blade 1.
However, as electrochemical machining is not a mechanical machining process, it is merely necessary for the part to be correctly positioned during machining, unlike in conventional machining where it is necessary for the part to be very firmly locked on the stand.